Aerodynamic Drag Reducing Apparatus

ABSTRACT

An aerodynamic drag reducing apparatus for use with vehicles having downstream surfaces that are not streamlined. The apparatus includes folding panels that extend rearward for use in a drag reducing configuration and collapse for use in a space saving configuration.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/618,322, filed Nov. 13, 2009, which is a continuation of U.S. patentapplication Ser. No. 12/045,022, filed Mar. 9, 2008 and issued as U.S.Pat. No. 7,618,086 on Nov. 17, 2009, which is a continuation-in-part ofU.S. patent application Ser. No. 11/565,254, filed Nov. 30, 2006 andissued as U.S. Pat. No. 7,374,230 on May 20, 2008, which claims thebenefit of U.S. Provisional Patent Application No. 60/741,155, filedDec. 1, 2005, which applications are all hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present invention relates to an aerodynamic drag reducing apparatusfor use with vehicles having downstream surfaces that are notstreamlined. Examples include: over-the-road trucks and truck trailers,vans and minivans, motor homes and travel trailers, and pickup trucks.In vehicles such as pickup trucks, one non-streamlined surface is nearthe center of the vehicle. The present invention is suitable for usewith vehicles having rear doors.

BACKGROUND

It is known that a significant amount of aerodynamic drag is createdwhen a vehicle travels at velocities typical on a modern roadway. Thisis due, in large part, to areas of low pressure that are induced on rearsurfaces of the vehicle. The low pressure becomes more pronounced asairflow over the vehicle separates from the vehicle surfaces. Thephenomenon of airflow separation is also well known in aircraft wingdesign and, in this case, causes the wing to stall.

Vehicles having blunt rear ends are especially affected by airflowseparation starting at an abrupt transition to a rear—near verticalsurface. The low pressure that the airflow separation induces iscompounded by a relatively large area on which the low air pressure actsin comparison with more streamlined vehicles.

The low air pressure acting on the rear surfaces of a moving vehicleproduces a force that resists forward motion of the vehicle. This forceis opposed by the vehicle's engine and requires power that is typicallyproduced by burning fuel. Any reduction in aerodynamic drag results in areduction in fuel consumption.

In a current era of high fuel prices and increasing environmentalconsciousness, fuel efficiency improvements are a growing concern.Aerodynamic improvements are especially valuable since they can becombined with other improvements such as engine efficiency and reducedchassis weight. Increasing fuel efficiency also provides the valuablebenefit of increasing a vehicle's range of travel between refueling.

The present disclosure employs a technique of adding tapered rearsurfaces to a vehicle, A similar streamlining principle is practicedwith other vehicles such as high-speed cars and airplanes. It has alsobeen applied to over-the-road trucks where the tapered rear surfaces arecollectively known as a “boat-tail”.

SUMMARY

The present disclosure is concerned with providing an aerodynamic dragreducing apparatus for vehicles with a purpose of reducing energyconsumption. More specifically, this is achieved by adding gentlysloping surfaces downstream of rear facing surfaces of the vehicle witha goal of reducing airflow separation and aerodynamic drag. This, inturn, reduces fuel consumption of the vehicle.

On certain vehicles, simply adding the required additional surfaceswould result in a substantial increase to the vehicle's length. Thislength would be acceptable, in many cases, on the open road inuncongested traffic, but would be impractical on crowded urban roadways,in parking lots, in campgrounds, and by loading docks. To address this,the present disclosure has two primary configurations. The firstconfiguration is an extended configuration that reduces drag and fuelconsumption, especially at highway speeds. The second configuration is aretracted configuration that provides much less, if any, drag reduction,but results in a more compact vehicle that is practical in crowdedareas. This combination of configurations in the same apparatus isespecially useful since zones of higher speed traffic are often notcongested. These high-speed zones are also where the drag reducingpotential is the highest. Likewise, congested areas often have reducedtraffic speed with less drag reducing potential, but in these cases, theretracted configuration may be required for maneuvering.

In order to easily and conveniently convert between the refractedconfiguration and the extended configuration, the present disclosureemploys panels that fold as part of an apparatus attached to the roar ofthe vehicle.

To accommodate vehicles where access to the rear of the vehicle isrequired, certain embodiments of the present disclosure allow theapparatus to be temporarily moved without removal from the vehicle, Incertain embodiments, a single whole apparatus is mounted on a supportpanel, door, or framework that, in turn, is mounted on a hinge, linkage,or linear slide. Other embodiments of the present disclosure have anoverall aerodynamic shape split into two halves, These halves can bemounted on hinges and opened, providing access to the rear of thevehicle. Optionally, the halves can be integrated with rear doors of thevehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The benefits and advantages of the present disclosure will become morereadily apparent to those of ordinary skill in the relevant art afterreviewing the following detailed description and accompanying drawings,wherein:

FIGS. 1A through 1M show a first embodiment of the present disclosurerear mounted on an over-the-road trailer in various configurations. Inthis embodiment, an aerodynamic drag reducing apparatus is in twohalves, split right and left. The right and left halves can be openedfor access to the rear of the trailer. In particular:

FIGS. 1A through 1F are all views sharing the same perspective from theleft rear corner. In particular:

FIG. 1A shows the apparatus in a fully extended configuration with rightand left trailer doors closed.

FIG. 1B shows the apparatus in a fully refracted configuration with thetrailer doors closed.

FIGS. 1C through 1F are enlarged partial views of the same scale. Inparticular:

FIG. 1C shows the apparatus in the fully retracted configuration withthe trailer doors closed.

FIG. 1D shows the right apparatus half in a fully extended configurationwith its trailer door closed and the left apparatus half in a fullyretracted configuration with its trailer door open.

FIG. 1E shows the apparatus in the fully retracted configuration withthe trailer doors opened.

FIG. 1F shows the apparatus in a partially retracted configuration withthe trailer doors closed.

FIGS. 1G through 1I are all enlarged partial left elevation views of thesame scale shown with the trailer doors closed. In particular:

FIG. 1G shows the apparatus in the fully extended configuration.

FIG. 1H shows the apparatus in the partially retracted configuration.

FIG. 1I shows the apparatus in the fully retracted configuration.

FIGS. 1J through 1M are all enlarged partial top plan views of the samescale. In particular:

FIG. 1J shows the apparatus in the frilly extended configuration withthe trailer doors closed.

FIG. 1K shows the apparatus in the partially refracted configurationwith the trailer doors closed. The tight apparatus half has itsnon-vertical panels removed for the purpose of illustration.

FIG. 1L shows the apparatus in the fully refracted configuration withthe trailer doors closed.

FIG. 1M shows the apparatus in the fully refracted configuration withthe trailer doors opened.

FIGS. 2A through 2D are all perspective views showing the rightapparatus half of FIGS. 1A through 1M by itself in variousconfigurations. In this embodiment of the present disclosure, two panelgroups are shown. The larger group is attached to the right door of thetrailer on its large end, and the smaller group is attached to a rearpanel of the larger group (that is the panel farthest from the trailerdoor). In particular:

FIGS. 2A and 2B share the same scale and view perspective from the lightrear corner. In particular:

FIG. 2A shows both panel groups in the fully retracted configuration.

FIG. 2B shows both panel groups in the fully extended configuration.

FIGS. 2C and 2D share the same scale and partly show the interior of theapparatus with both panel groups in the partially retractedconfiguration. In particular:

FIG. 2C is a view from the left rear corner.

FIG. 2D is a view from the left front corner.

FIGS. 3A through 3D are all perspective views showing one of the twopanel groups of FIGS. 2A through 2D in the fully extended configuration.In particular:

FIGS. 3A and 3B share the same view perspective from the right rearcorner. In particular:

FIG. 3A shows the larger panel group of FIGS. 2A through 2D.

FIG. 3B shows the smaller panel group of FIGS. 2A through 2D.

FIGS. 3C and 3D share the same scale and view perspective from the leftrear corner and partly show the interior of the panel group. Inparticular:

FIG. 3C shows the smaller panel group of FIGS. 2A through 2D.

FIG. 3D shows the larger panel group of FIGS. 2A through 2D.

FIGS. 4A through 4F are all perspective views of the same scale, showingseveral panels of the panel group of FIGS. 3A and 3D. Panels that arenot near the large end of the panel group have been removed for thepurpose of illustration. In particular:

FIGS. 4A through 4C share the same view perspective from the left rearcorner. In particular:

FIG. 4A shows the panels in the fully extended configuration.

FIG. 4B shows the panels in the partially refracted configuration.

FIG. 4C shows the panels in the fully refracted configuration.

FIGS. 4D through 4F share the same view perspective from the right rearcorner. In particular:

FIG. 4D shows the panels in the fully extended configuration.

FIG. 4E shows the panels in the partially retracted configuration.

FIG. 4F shows the panels in the fully retracted configuration.

FIGS. 5A through 5D are all perspective views of the same scale as FIGS.4A through 4F, showing several panels of the panel group of FIGS. 3A and3D. Side panels have been removed for the purpose of illustration. Inparticular:

FIGS. 5A through 5C have the same view perspective as FIGS. 4D through4F. In particular:

FIG. 5A shows the panels in the fully extended configuration.

FIG. 5B shows the panels in the partially retracted configuration.

FIG. 5C shows the panels in the fully refracted configuration.

FIG. 5D has the same view perspective as FIGS. 4A through 4C and showsthe panels in the fully extended configuration.

FIGS. 6A through 6D are all perspective views of the same scale as FIGS.4A through 4F, showing several panels of the panel group of FIGS. 3A and3D). Top and bottom panels have been removed for the purpose ofillustration. In particular:

FIGS. 6A and 6B show the panels in the fully extended configuration. Inparticular:

FIG. 6A has the same view perspective as FIGS. 4A through 4C.

FIG. 6B has the same view perspective as FIGS. 4D through 4F.

FIGS. 6C and 6D show the panels in the partially retractedconfiguration. In particular:

FIG. 6C has the same view perspective as FIGS. 4A through 4C.

FIG. 6D has the same view perspective as FIGS. 4D through 4F.

FIG. 7 has the same view perspective and scale as FIGS. 4D through 4Fand shows several panels of the panel group of FIGS. 3A and 3D in thefully retracted configuration. The top, bottom, and rear panels havebeen removed for the purpose of illustration.

FIGS. 8A and 8B are enlarged views of the same scale, showing the panelgroup of FIGS. 3A and 3D in the fully retracted configuration. Inparticular:

FIG. 8A has the same view perspective as FIGS. 4D through 4F.

FIG. 8B is a right elevation view.

FIGS. 9A through 9N are all views with the same perspective and scale asFIG. 8A, showing individual panels of the panel group of FIGS. 3A, 3D,8A, and 8B. The configuration specific orientation of each panel is fromthe panel group in the fully retracted configuration (as shown at FIG.8A). In particular:

FIG. 9A shows a front panel.

FIG. 9B shows a forward-most top panel.

FIG. 9C shows a forward-most bottom panel.

FIG. 9D shows a forward-most upper triangular panel.

FIG. 9E shows a forward-most lower triangular panel.

FIG. 9F shows a forward-most side panel.

FIG. 9G shows a middle top panel.

FIG. 9H shows a middle bottom panel.

FIG. 9I shows a rearmost upper triangular panel.

FIG. 9J shows a rearmost lower triangular panel.

FIG. 9K shows a rearmost side panel.

FIG. 9L shows the rear panel.

FIG. 9M shows a rearmost top panel.

FIG. 9N shows a rearmost bottom panel.

FIGS. 10A through 10C are all perspective views sharing the same scaleand perspective from the left rear corner, showing a panel group from asecond embodiment of the present disclosure in various configurations.In this embodiment, an aerodynamic drag reducing apparatus is not splitin two halves, but is formed of panel groups that span a vehicle. Inparticular:

FIG. 10A shows the panel group in a fully extended configuration.

FIG. 10B shows the panel group in a partially retracted configuration.

FIG. 10C shows the panel group in a fully retracted configuration.

FIG. 11 is a perspective view from the left rear corner, showing a pairof panel groups from a third embodiment of the present disclosure in afully extended configuration. In this embodiment, an aerodynamic dragreducing apparatus is split in two halves, one upper and one lower.

FIGS. 12A through 12C are all perspective views sharing the same scaleand perspective from the left rear corner, showing the lower panel groupof FIG. 11. In particular:

FIG. 12A shows the panel group in a fully extended configuration.

FIG. 12B shows the panel group in a partially retracted configuration.

FIG. 12C shows the panel group in a fully retracted configuration.

FIGS. 13A through 13C are all perspective views sharing the same scaleand perspective as FIGS. 12A through 12C, showing the upper panel groupof FIG. 11. In particular:

FIG. 13A shows the panel group in the fully extended configuration.

FIG. 13B shows the panel group in the partially retracted configuration.

FIG. 13C shows the panel group in the fully retracted configuration.

FIGS. 14A through 14D are all perspective views sharing the same scale,showing a framed panel group from a forth embodiment of the presentdisclosure. A covering of the framed panel group is not shown for thepurpose of illustration. In particular:

FIGS. 14A through 14C have the same scale and view perspective as theircounterparts at FIGS. 5A through 5C. In particular:

FIG. 14A shows the framed panel group in a fully extended configuration.

FIG. 14B shows the framed panel group in a partially refractedconfiguration.

FIG. 14C shows the framed panel group in a fully refractedconfiguration.

FIG. 14D has the same scale and perspective as its counterpart at FIG.5D and shows the framed panel group in the fully extended configuration.

FIGS. 15A and 15B are enlarged perspective views showing three topframed panels and their covering from the framed panel group of FIGS.14A through 14D in a partially retracted configuration. In particular:

FIG. 15A is a view from the upper right corner primarily showing anexterior of the framed panels.

FIG. 15B is a view from the lower right corner primarily showing aninterior of the framed panels.

FIGS. 16A through 16E are enlarged partial views illustrating typicalfolding fabric panel joints. In particular:

FIG. 16A is a perspective view illustrating a fully dosed joint with thefabric wrapping around the joined panels.

FIG. 16B through 16E illustrates a joint with the fabric folding betweenthe joined panels with a joint-stop and bias spring as optionalfeatures. In particular:

FIG. 16B is a perspective view illustrating a partially opened foldingfabric joint.

FIGS. 16C through 16E are views perpendicular to a folding axis of thefolding fabric joint. In particular:

FIG. 16C illustrates the folding fabric joint fully opened, held by thejoint-stop and compressing the bias spring.

FIG. 16D illustrates the folding fabric joint partially opened,contacting the bias spring.

FIG. 16E illustrates the folding fabric joint fully closed.

FIG. 17 is a perspective view from the left rear corner, showing a setof four panel groups from a fifth embodiment of the present disclosurein a fully extended configuration. In this embodiment, an aerodynamicdrag reducing apparatus is split into four quarters.

FIGS. 18A through 18D are all perspective views sharing the same scaleof FIG. 17 and showing a tower left quarter panel group of FIG. 17. Inparticular:

FIGS. 18A and 18B share the same view perspective from the left rearcorner and primarily show an exterior of the lower left quarter panelgroup. In particular:

FIG. 18A shows the lower left quarter panel group in a fully retractedconfiguration.

FIG. 18B shows the lower left quarter panel group in a partiallyrefracted configuration.

FIGS. 18C and 18D share the same view perspective from the right frontcorner and primarily show the interior of the lower left quarter panelgroup. In particular:

FIG. 18C shows the lower left quarter panel group in the same partiallyretracted configuration as FIG. 18B.

FIG. 18D shows the lower left quarter panel group in the fully extendedconfiguration of FIG. 17.

FIGS. 19A and 19B are left rear perspective views showing a sixthembodiment of the present disclosure rear mounted on the over-the-roadtrailer with the right and left trailer doors closed. In thisembodiment, a simplified aerodynamic drag reducing apparatus is in twohalves, split right and left. The right and left halves can be openedfor access to the rear of the trailer. In particular:

FIG. 19A shows the apparatus in a fully extended configuration.

FIG. 19B shows the apparatus in a fully retracted configuration.

FIGS. 20A through 20F are all perspective views of the same scaleshowing the right apparatus half of FIGS. 19A and 19B by itself invarious configurations. In particular:

FIGS. 20A through 20C share the same view perspective from the left rearcorner. In particular:

FIG. 20A shows primarily an interior of the right apparatus half in thefully extended configuration.

FIG. 20B shows the right apparatus half in a partially refractedconfiguration.

FIG. 20C shows the right apparatus half in the fully refractedconfiguration.

FIGS. 20D through 20F share the same view perspective from the rightrear corner and show primarily an exterior of the right apparatus half.In particular:

FIG. 20D shows the right apparatus half in the fully extendedconfiguration.

FIG. 20E shows the right apparatus half in the partially retractedconfiguration.

FIG. 20F shows the right apparatus half in the fully refractedconfiguration.

FIGS. 21A through 21D show a seventh embodiment of the presentdisclosure rear mounted and adapted for use behind a sports-utilityvehicle. A fairing is included between the sports-utility vehicle and anaerodynamic drag reducing apparatus that is shown in a fully extendedconfiguration. In particular:

FIG. 21A is a perspective view from the left rear corner.

FIG. 21B is a left elevation view.

FIG. 21C is a partial top plan view.

FIG. 21D is a rear elevation view.

FIGS. 22A through 22C show the sports-utility vehicle, the fairing, andthe aerodynamic drag reducing apparatus of FIGS. 21A through 21D. Theaerodynamic drag reducing apparatus is shown in a fully retractedconfiguration. In particular:

FIG. 22A is a perspective view from the left rear corner.

FIG. 22B is a partial left elevation view.

FIG. 22C is a partial top plan view.

FIGS. 23A through 23C show a first section of the aerodynamic dragreducing apparatus of FIGS. 21A through 21D with view perspectives fromthe left rear corner. In particular:

FIG. 23A shows the first section of the apparatus in the fully extendedconfiguration.

FIG. 23B shows the first section of the apparatus in a partiallyrefracted configuration.

FIG. 23C shows the first section of the apparatus in the fully retractedconfiguration.

FIGS. 24A and 24B are partial views showing a sub-set of frames andjoints of the first section of FIGS. 23A through 23C of the aerodynamicdrag reducing apparatus of FIGS. 21A through 21D with a common viewperspective from the top left corner. In particular:

FIG. 24A shows the sub-set of frames and joints in the fully extendedconfiguration.

FIG. 24B shows the sub-set of frames and joints in the fully retractedconfiguration.

DETAILED DESCRIPTION

While the present invention is susceptible of embodiment in variousforms, there are shown in the drawings and will hereinafter be describedpresently 30 preferred embodiments with the understanding that thepresent disclosure is to be considered an exemplification of theinvention and is not intended to limit the invention to the specificembodiments illustrated.

The embodiments presented are also shown in various forms and shapes andwith various optional features in various combinations. These variationsalso are exemplifications of the invention and are not intended to limitthe combinations of forms, shapes, and optional features.

The present invention is suited for use behind vehicles with vertical ornear vertical rear facing surfaces and serves to streamline the vehiclewhen in an extended configuration. When necessary, the present inventioncan transform into a retracted configuration to save space. The abilityto form two configurations and transform from one to the other withoutdisassembly is made possible by the strategic use of folding panels inan apparatus as described below.

In the present disclosure, the folding panels are arranged into panelgroups. Multiple panel groups may be attached to each other in seriesfrom front to back within a same apparatus. The panel groups may beindividually extended or retracted. When all panel groups are fullyextended, the apparatus itself is fully extended and is in a first ofits primary configurations. Likewise, when all the panel groups arefully retracted, the apparatus itself is fully retracted and is in asecond of its primary configurations. When at least one panel group isextended and at least one panel group is refracted, the apparatus is ina secondary configuration. In certain embodiments, the apparatus caninclude only a single panel group. In this case, the concept of the“secondary configuration” does not apply. Likewise, the definition of“primary configuration” extends to a panel group but the definition of“secondary configuration” does not.

The panels of the panel groups and folding joints between them supportloads imposed on the apparatus by gravity, airflow, uneven roads, andother operational causes. The panels may depend on a framework ormultiple frameworks for structural support, or they may serve as theirown structural support. The folding joints and structural connectionsbetween the panels may take the form of a simple or complex hinge; alinkage; a spherical joint; a sliding spherical joint; a fibrousmaterial, such as fabric or cord; or a solid deformable material, suchas plastic. The same apparatus may use both framed and non-framed panelsas well as a mixture of joint types.

The folding panels are employed to allow the apparatus to transformbetween an extended and retracted configuration. The folding joints maytake various forms as discussed above and below in any of theembodiments. Furthermore, a given apparatus may employ any of thefolding joint forms in any combination. To simplify the discussion inthis disclosure, the term “fold-line” is used to represent the foldingaction of any of the various joint types.

In certain embodiments of the present disclosure, joints between certainpanel pairs may both rotate along a hinge-line and linearly slide alongthe same hinge-line. This type of hinge-line is also considered to be a“fold-line”. In other embodiments, particularly those that use a fibrousor solid deformable material as a structural connection between panels,multiple rotational and linear movements can occur between the panels,approximated by a fold-line and dominated by the folding rotation.

In certain embodiments of the present disclosure, flexible material,such as fabric, may be used to cover framework, forming a framed panelas illustrated at FIGS. 15A and 15B. The flexible material may extendfrom panel to panel and serve to keep dirt and debris from entering theinterior of the apparatus. This is also illustrated at FIGS. 15A and15B. In certain embodiments, the entire apparatus may be covered by asingle continuous piece of flexible material. Optionally, the flexiblematerial may also serve as a structural connection between certain panelpairs as mentioned in the preceding paragraphs and as illustrated atFIGS. 16A through 16E. Flexible material may be located inside and/oroutside the panel framework and can fully or partially form the interiorand/or exterior of the apparatus. The flexible material can serve toseal the joints, making the apparatus substantially airtight. Theflexible material can be connected to each of the panels or frameworks,not connected to any of the panels or frameworks, or connected to selectpanels or frameworks.

An airtight apparatus can be filled with air or other gas as a method ofextending the apparatus. Likewise, the air or other gas can be evacuatedto retract the apparatus.

In certain embodiments of the present disclosure, joints between panelsmay be spring-loaded, as illustrated at FIGS, 16B through 16E. Thesprings can assist in the extension and/or retraction of the panelgroups. Bi-stable springs can also be used that serve to extend andretract the panel groups. The joints can also have detents that aid inmaintaining the apparatus in one or both of the primary configurations.

In certain embodiments of the present disclosure, removable parts may beattached to the panels or panel frameworks to keep them in a primaryconfiguration. These parts can be fastened to the panels or panelframeworks by threaded fasteners, latches, hooks, or other means. Incertain embodiments, the same removable parts may be used to keep boththe extended and retracted configurations by attaching them in adifferent sequence and joining the features of the panels and theremovable parts in different combinations.

Other optional features that can be used separately or together includejoint-stops that keep the panel groups from reaching an undesiredconfiguration, as illustrated at FIGS. 16B through 16E; latches thatkeep the apparatus in the primary configurations; and retraction andextension devices.

In certain embodiments of the present disclosure, pulleys and cablesand/or other optional components may be used in a retraction andextension device either separately or together. These include pneumaticand hydraulic cylinders, linear drives, electric motors, gear sets,cord, chain, webbing, cams, and springs.

In certain embodiments of the present disclosure, certain panels orpanel frameworks may deform from one configuration to the next or whiletransitioning between configurations. In certain cases, this isnecessary to avoid kinematic lockup. This deformation will cause forcesand moments to develop within and between the panels. These forces andmoments may be employed to keep the panel groups stable in one or bothprimary configurations.

Referring now to the figures, in particular to FIGS. 1A through 1M,there is shown a first embodiment of the present disclosure mounted onan exemplary over-the-road trailer 1. More specifically, a left handapparatus 302 and a right hand apparatus 303 are mounted and shown invarious configurations. FIGS. 2A through 2D) show the right handapparatus 303 in detail and in various configurations. In the presentembodiment, a right rear trailer door serves as a mounting platform forthe right hand apparatus 303 and can also be integrated to become partof the apparatus 303. An exterior shape of the left hand apparatus 302is a mirror image of an exterior shape of the right hand apparatus 303.Essentially the same relationships between the left hand door and theleft hand apparatus 302 exist as mentioned above for the right. To gainaccess to a cargo holding area 1 a of the trailer 1, the apparatuses 302and 303 are opened as typical trailer doors or with the trailer doors.

If the apparatuses 302 and 303 are symmetric in a vertical direction, asthey are shown at FIGS. 1A through 1M, they can be essentially identicalwith each other. In this case, the apparatuses 302 and 303 are simplyassembled to their respective trailer doors upside down and rotatedone-half turn from each other.

As mentioned above, the apparatuses 302 and 303 are normally used in oneof two primary configurations, fully extended and fully retracted. FIG.1A illustrates the fully extended configuration and FIG. 1B illustratesthe fully retracted configuration.

In certain panels of certain embodiments of the present disclosure,clearance cuts 339 may be required to avoid interference with thevehicle, hinges, latches, and other panels. For example, FIG. 9F showsclearance cuts 339 made on a panel 323 to avoid interference with a setof trailer door hinges.

FIGS. 2A through 2D and 3A through 3D illustrate that the panels arearranged in panel groups 311 and 312 having a front and a rear. Thepanel groups 311 and 312 combine to form the apparatus 303. The front ofthe panel group 311 farthest upstream attaches to the right rear door ofthe trailer 1 or the rear facing surfaces of the vehicle as appropriate.The front of the following panel group 312 attaches to the rear of thepanel group 311 ahead of it. In these illustrations, only the two panelgroups 311 and 312 are shown. In other embodiments of the presentdisclosure, one panel group may be used alone in an apparatus, or morethan two panel groups may be assembled in succession within anapparatus. Mating features between the panel groups 311 and 312,specifically forward mating features of the reward group 312 andrearward mating features of the forward group 311, can be integratedinto a single structure serving the requirements of both groups 311,312.FIGS. 2A through 2D show two panel groups 311 and 312 connected to eachother, as they would be in operation. FIGS. 3A and 3D show the largerpanel group 311 by itself. Likewise, FIGS. 3B and 3C show the smallerpanel group 312 by itself.

The panel groups 311 and 312 are similar to each other in regards to thefunction of their corresponding top and side panels 321, 322, 323, 324,325, 326, 327, 328, 329, 330, 331, and 333. The fold-lines 340, 341,342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355,356, 357, 358, and 359, illustrated at FIGS. 9A through 9N, are alsosimilar in function to their corresponding fold-lines from other panelgroups 311 and 312. Furthermore, a front panel 320 is similar infunction between the panel groups 311 and 312 in that it connects to oris integrated with what comes immediately in front of it. This could beeither the trailer door or a rear panel 332 from the panel group 311that precedes it. Likewise, the rear panel 332 is similar in functionbetween the panel groups 311 and 312 in that it connects to or isintegrated with the front panel of the panel group 312 immediatelybehind it. In the case of the last panel group 312, the rear panel is anexterior panel of the apparatus 302 and 303. The panels belonging topanel groups farther forward (e.g., the panel group 311) are typicallylarger than their corresponding panels belonging to more rearward panelgroups (e.g., the panel group 312).

FIGS. 4A through 4F, 5A through 5D, 6A through 6D, and 7 illustrate theworkings of the panel group 311 of a typical embodiment of the presentdisclosure. This illustration is done by removing certain panels of thepanel group 311 from each illustration. Even though different panels arehidden from each illustration, the shape and size of all panels,including the hidden panels, along with the location of their respectivefold-lines are used to calculate the kinematic position of each panelthroughout its range of motion in each illustration, Isolating andstudying the relationships between certain sub-groups of panelsclarifies the function each individual panel and its respectivefold-line(s) has in the panel group 311. These descriptions and figuresare based on a specific panel group 311 of a specific embodiment of thepresent disclosure for the purposes of illustration only. Otherembodiments of the present disclosure and even other panel groups withinthe present embodiment will have different proportions and features thanthose shown. Panel groups of other embodiments of the present disclosurewill have different relationships between the panels and can havedifferent quantities of panels. In addition, as mentioned above,frameworks and/or framed panels can be substituted for any or all of thepanels.

FIGS. 4A through 4F illustrate the relationships between the front panel320, a forward-most top panel 321, a forward-most upper triangular panel322, a forward-most side panel 323, a forward-most lower triangularpanel 324, and a forward-most bottom panel 325. These panels 320, 321,322, 323, 324, and 325 are also shown individually with their respectivefold-lines at FIGS. 9A through 9F. The panels 320, 321, 322, 323, 324,and 325 are connected to each other by fold-lines as follows: Fold-line340 connects the front panel 320 (FIG. 9A) to the forward-most top panel321 (FIG. 9B). Likewise, fold-line 342 connects the front panel 320(FIG. 9A) to the forward-most bottom panel 325 (FIG. 9C). Fold-line 341connects the front panel 320 (FIG. 9A) to the forward-most side panel323 (FIG. 9F). Fold-line 347 connects the forward-most side panel 323(FIG. 9F) to the forward-most upper triangular panel 322 (FIG. 9D).Likewise, fold-line 348 connects the forward-most side panel 323 (FIG.9F) to the forward-most lower triangular panel 324 (FIG. 9E). Fold-line343 connects the forward-most top panel 321 (FIG. 9B) to theforward-most upper triangular panel 322 (FIG. 9D). Likewise, fold-line344 connects the forward-most bottom panel 325 (FIG. 9C) to theforward-most lower triangular panel 324 (FIG. 9E). This arrangement offold-lines 340, 341, 342, 343, 344, 347, and 348 and panels 320, 321,322, 323, 324, and 325 results in a coordinated deployment of the panelgroup 311 from the fully retracted to the fully extended configurationsand a coordinated stowage of the panel group 311 from the fully extendedto the fully retracted configurations. The configuration of panels 320,321, 322, 323, 324, and 325 within this sub-group is determined by asingle variable. Thus, by controlling the angle across any fold-line340, 341, 342, 343, 344, 347, or 348, the angles across the remainingfold-lines 340, 341, 342, 343, 344, 347, and 348 are determined and theconfiguration of the panels 320, 321, 322, 323, 324, and 325 is known.

FIGS. 5A through 5D illustrate the relationships between the front panel320, the forward-most top panel 321, the forward-most bottom panel 325,a middle top panel 326, a middle bottom panel 330, a rearmost top panel331, the rear panel 332, and a rearmost bottom panel 333. These panels320, 321, 325, 326, 330, 331, 332, and 333 are also shown individuallywith their respective fold-lines at FIGS. 9A through 9C, 9G, 9H, and 9Lthrough 9N. The panels 320, 321, 325, 326, 330, 331, 332, and 333 areconnected to each other by fold-lines as follows: The fold-line 340connects the front panel 320 (FIG. 9A) to the forward-most top panel 321(FIG. 913). Likewise, the fold-line 342 connects the front panel 320(FIG. 9A) to the forward-most bottom panel 325 (FIG. 9C). Fold-line 345connects the forward-most top panel 321 (FIG, 98) to the middle toppanel 326 (FIG. 9G). Likewise, fold-line 346 connects the forward-mostbottom panel 325 (FIG. 9C) to the middle bottom panel 330 (FIG. 9H).Fold-line 350 connects the middle top panel 326 (FIG. 9G) to therearmost top panel 331 (FIG. 9M). Likewise, fold-line 351 connects themiddle bottom panel 330 (FIG. 9H) to the rearmost bottom panel 333 (FIG.9N). Fold-line 355 connects the rearmost top panel 331 (FIG. 9M) to therear panel 332 (FIG. 9L). Likewise, fold-line 356 connects the rearmostbottom panel 333 (FIG. 9N) to the rear panel 332 (FIG. 9L). Unlike thepreceding sub-group, this sub-group of panels 320, 321, 325, 326, 330,331, 332, and 333 by themselves does not form a configuration that canbe determined by a single variable. Instead, this sub-group relies onthe panel group 311 as a whole to determine its configuration.

FIGS. 6A through 6D illustrate the relationships between the front panel320, the forward-most upper triangular panel 322, the forward-most sidepanel 323, the forward-most lower triangular panel 324, a rearmost uppertriangular panel 327, a rearmost side panel 328, a rearmost lowertriangular panel 329, and the rear panel 332. These panels 320, 322,323, 324, 327, 328, 329, and 332 are also shown individually with theirrespective fold-lines at FIGS. 9A, 9D through 9F, and 91 through 9L. Thepanels 320, 322, 323, 324, 327, 328, 329, and 332 are connected to eachother by fold-lines as follows: The fold-line 341 connects the frontpanel 320 (FIG. 9A) to the forward-most side panel 323 (FIG. 9F). Thefold-line 347 connects the forward-most side panel 323 (FIG. 9F) to theforward-most upper triangular panel 322 (FIG. 9D). Likewise, thefold-line 348 connects the forward-most side panel 323 (FIG. 9F) to theforward-most lower triangular panel 324 (FIG. 9E). Fold-line 349connects the forward-most side panel 323 (FIG. 9F) to the rearmost sidepanel 328 (FIG. 9K). Fold-line 352 connects the rearmost side panel 328(FIG. 9K) to the rearmost upper triangular panel 327 (FIG. 91).Likewise, fold-line 353 connects the rearmost side panel 328 (FIG. 9K)to the rearmost lower triangular panel 329 (FIG. 91). Fold-line 354connects the rearmost side panel 328 (FIG. 9K) to the rear panel 332(FIG. 9L). As with the preceding sub-group, this sub-group of panels320, 322, 323, 324, 327, 328, 329, and 332 by themselves does not form aconfiguration that can be determined by a single variable. Thissub-group also relies on the panel group 311 as a whole to determine itsconfiguration. In this example embodiment, the rearmost upper and lowertriangular panels 327 and 329 must fold to prevent interference betweenthemselves and the rearmost top and bottom panels 331 and 333respectively. This folding is needed during a portion of theextension-retraction process and can be most clearly observed at FIGS.2C and 2D. The position of the rearmost upper and lower triangularpanels 327 and 329 is determined by their contact with the rearmost topand bottom panels 331 and 333 respectively or by a joint-stop keepingthem parallel with the rearmost side panel 328. The related fold-lines352 and 353 can be spring-loaded, keeping the panels 327 and 329 againsttheir respective stops until contact is made with the rearmost top andbottom panels 331 and 333 respectively.

In the case that the front panel of the rearward panel group 312 and therear panel 332 of the preceding panel group 311 are integrated,additional fold-lines will be found on the combined panel to serve theircorresponding purpose for both panel groups 311 and 312. This isillustrated at FIG. 9L where fold-lines 357, 358, and 359 are present.These fold-lines 357, 358, and 359 serve the same purpose as fold-lines340, 341, and 342 as shown at FIG. 9A, but for the following panel group312.

The panel group 311, with all panels 320, 321, 322, 323, 324, 325, 326,327, 328, 329, 330, 331, 332, and 333 present, forms an assembly whoseconfiguration is determined by a single variable. This is of greatbenefit whether the apparatuses 302 and 303 are deployed manually or byautomated means, as each panel group can be managed with a singlevariable rather than as multiple individual panels. Furthermore, it ispossible to coordinate the panel groups 311, 312 with each other so thatthe configuration of the entire apparatus 303 or pair of apparatuses302, 303 can be managed by a single variable.

The discussions above focus primarily on an embodiment of the presentdisclosure suited for vehicles with rear doors having verticalhinge-lines served by two apparatuses 302 and 303. Vehicles and trailerswith neither rear doors nor need for access to the rear of the vehicleare better served by a second embodiment of the present disclosure thatspans the width of the vehicle. This embodiment is formed by combiningthe two apparatuses 302 and 303, at their common edges, into a singleapparatus, as illustrated by the panel group 411 at FIGS. 10A through10C. More specifically, the right hand and left hand versions of thepanel group 311 are combined by joining the common edges of the front,rear, top, and bottom panels 320, 321, 325, 326, 330, 331, 332, and 333.As in the previous embodiment, multiple panel groups can be arranged onebehind the other to form an extended apparatus. As in the precedingpanel groups 311 and 312, the configuration of the combined panel group411 is also controlled by a single variable.

The embodiment of the preceding paragraph may be adapted for use withvehicles having rear doors by mounting the combined apparatus on asupport panel, door, or framework that in turn is mounted on a hinge,linkage, or linear slide, The whole apparatus can thus be temporarilymoved when access to the rear of the vehicle is required.

A third embodiment of the present disclosure is arrived at by splittingthe apparatus in the preceding paragraph, exemplified by panel group411, about a horizontal plane near its center, creating two halves: oneupper apparatus and one lower apparatus. This embodiment is illustratedby the panel groups 511 and 611 shown at FIGS. 11, 12A through 12C, and13A through 13C. This embodiment is suited for use on vehicle doors withhorizontal hinges. This embodiment could also be rotated ninety degreesand used on vehicles whose doors have vertical hinges. As in theprevious embodiments, panel groups in successively smaller sizes can beconnected one behind the other to extend the gently sloping surfaces andreduce the rear-facing area of the vehicle in the fully extendedconfiguration. This embodiment retains the desirable characteristics ofstability and configuration by a single variable. Panel groups of thisembodiment can be used individually. For example, the panel group 611 atFIGS. 13A through 13C could be used behind the cab of a pickup truck.

A fourth embodiment of the present disclosure includes panels and/orframed panels 721, 722, 724, 726, and 731 combined to form a panel group711 as illustrated at FIGS. 14A through 14D, 15A and 15B. Coverings 750,751, and 752 (not shown at FIGS. 14A through 14D) are formed of flexiblematerial and attached to certain areas of certain panels 721, 722, 724,726, and 731. Certain coverings 750 and 752 may attach to and/or covertwo or more panels or framed panels 721, 722, 724, 726, and 731. Certainforms of the current embodiment have a single covering substantiallyforming the exterior surface of the apparatus. Certain panels and framedpanels may not attach to the covering but serve to provide a shape andstructural support for it. Certain panels, such as counterparts topanels 327 and 329 (illustrated at FIGS. 3A and 3D), are not required bythis embodiment. Other panels 722 and 724 (counterparts to panels 322and 324 also illustrated at FIGS. 3A and 3D) may take a shape that doesnot fully fill the apparatus' exterior when it is fully extended butstill provide required structural and kinematic support. In these cases,the exterior shape of the extended apparatus in these areas isdetermined by the panels and/or framed panels adjoining the removed orreduced panels. A covering can span any void created by the removed orreduced panels in the extended configuration and attach to other panelsof the apparatus. The present embodiment may be adapted to and combinedwith the other embodiments of the present disclosure.

A fifth embodiment of the present disclosure can be arrived at bysplitting the third embodiment about a vertical plane near its center asillustrated by FIGS. 17 and 18A through 18D. This embodiment retains thedesirable characteristics of stability and configuration by a singlevariable. In contrast to certain embodiments above which combine a pairof apparatuses to cover the rear surface of a vehicle, this embodimentrequires four apparatuses 512, 513, 612, and 613 arranged in quarters.In the example of the pickup truck, only the upper two quarters 612 and613 would be required. Just as in the embodiments above, multiple panelgroups can be arranged one behind the other. This embodiment may becombined with the embodiment of the preceding paragraph. In this case,panel 629 is not required. The hole in the extended configuration cratedby the removal of panel 629 is spanned by a covering. The shape of thecovering over this hole when the apparatus is in the extendedconfiguration is determined by panel edges adjacent to the hole.

FIGS. 16A through 16E further illustrate the fabric joint type. Morespecifically, a first panel or framed panel 810 is joined by fabric 820which in turn is also joined to a second panel 830. Unlike a commonhinge, this joint type does not have a precisely defined hinge-line.Nonetheless, a folding action is made possible with sufficient precisionfor certain embodiments of the present disclosure.

Optional joint-stops 840 and bias springs 850, as illustrated at FIGS.16B through 16E, can be added to certain joints of any of the variousjoint types.

A sixth simplified embodiment of the present disclosure includes thefront panel 320 (FIG. 9A), the top panel 321 (FIG. 9B), the uppertriangular panel 322 (FIG. 9D), the side panel 323 (FIG. 9F, the lowertriangular panel 324 (FIG. 9E), and the bottom panel 325 (FIG. 9C). Theresulting apparatus takes a form similar to that shown at FIGS. 4Athrough 4F with no rear panel. A single variable defines theconfiguration of this apparatus as in the first sub-group discussedabove. In this embodiment, the top panel 321 and the bottom panel 325can be extended giving an extended top panel 321′ and an extended bottompanel 325′. FIGS. 19A and 19B illustrate the sixth embodiment. Left andright apparatuses 402, 403, including the extended top panel 321′ andthe extended bottom panel 325′, mount on the rear of the trailer 1 orthe trailer doors. FIGS. 20A through 20F further illustrate the rightapparatus 403 in various configurations and are similar to FIGS. 4Athrough 4F. In particular, FIGS. 19A, 20A, and 20D show the rightapparatus 403 in an extended configuration while FIGS. 19B, 20C, and 20Fshow the right apparatus 403 in a retracted configuration. In thisembodiment of the present disclosure, additional panel groups, asdescribed above, cannot be attached to the rear of the panels 321, 322,323, 324, and 325 (or 321′, 322, 323, 324, and 325′). As with the otherembodiments of the present disclosure, the front panel 320 can be aframework, can be integrated with the trailer door, or can be integratedwith the vehicle.

The panels 321′, 322, 323, 324, and 325′ of the apparatus 403 can bespring biased towards the retracted configuration. In certainembodiments, partial vacuum behind the moving trailer 1 overcomes thespring bias and automatically extends the left and right apparatuses402, 403. As the moving trailer 1 slows and stops, the spring bias againretracts the left and right apparatuses 402, 403. This method ofautomatically deploying and retracting the aerodynamic drag reducingapparatus can also be implemented on the other embodiments of thepresent disclosure.

A seventh example embodiment of the present disclosure is illustrated atFIGS. 21A through 22C. In particular, FIGS. 21A through 21D illustrate afairing 910 behind a sports-utility-vehicle (SUV) 901. The fairing 910joins and/or adapts the SUV 901 to a first framework group 911. Thefirst framework group 911 is joined to and followed by a secondframework group 912 that, in turn, is followed by a third frameworkgroup 913. The framework groups 911, 912, 913 are covered by a flexiblecovering similar to that described above. The flexible covering providesan aerodynamic drag reducing surface when the framework groups 911, 912,913 are in an extended configuration as illustrated at FIGS. 21A through21D. FIG. 21D illustrates that an exterior shape of the SUV 901 mayapproximately match an exterior shape of the framework groups 911, 912,913 in the extended configuration. FIGS. 22A through 22C illustrate theframework groups 911, 912, 913 in a refracted, space-saving,configuration.

The first framework group 911 is further illustrated at FIGS. 23Athrough 23C. The framework groups 912 and 913 are similar butprogressively smaller than the framework group 911. In the exampleembodiment, illustrated at FIGS. 23A through 23C, the first frameworkgroup 911 includes a front frame 920, a first left frame 921, a lefttriangular frame 922, a first top frame 923, a right triangular frame924, a first right frame 925, a second left frame 926, a second rightframe 927, a second top frame 928, a third left frame 929, a third rightframe 930, a fourth left frame 931, a rear frame 932, a fourth rightframe 933, a first bottom frame 934, a second bottom frame 935, and aright-to-left coordinating link 936. FIG. 23A illustrates the frameworkgroup 911 in the extended configuration. FIG. 23B illustrates theframework group 911 in a partially retracted configuration, and FIG. 23Cillustrates the framework group 911 in the retracted configuration.Similar to the embodiments discussed above, the seventh embodiment ofthe present disclosure relies on fold-lines between the frames 920, 921,922, 923, 924, 925, 926, 927, 928, 929, 930, 931, 932, 933, 934, 935,and the coordinating link 936 to transition between the extended and theretracted configurations.

FIGS. 24A and 24B further illustrate several relationships betweencertain frames 920, 922, 923, 924, and 925 and fold-lines joining them.In particular, the front frame 920 is connected to the first top frame923 at a hinge defining a fold-line 950. The front frame 920 is alsoconnected to the first right frame 925 at a hinge defining a fold-line952. The left triangular frame 922 is connected to the first top frame923 at a hinge defining a fold-line 954. Likewise, the right triangularframe 924 is connected to the first top frame 923 at a hinge defining afold-line 956. Other hinge connections between certain frames notillustrated at FIGS. 24A and 24B include connections between the frontframe 920 and the first left frame 921, the first left frame 921 and thesecond left frame 926, the first right frame 925 and the second rightframe 927, the second left frame 926 and the third left frame 929, thesecond right frame 927 and the third right frame 930, the third leftframe 929 and the fourth left frame 931, the third right frame 930 andthe fourth right frame 933, the fourth left frame 931 and the rear frame932, the fourth right frame 933 and the rear frame 932, first top frame923 and the second top frame 928, the second top frame 928 and the rearframe 932, the front frame 920 and the first bottom frame 934, the firstbottom frame 934 and the second bottom frame 935, and, finally, thesecond bottom frame 935 and the rear frame 932. The coordinating link936 can share a common hinge/fold-line with the second left frame 926and the third left frame 929 on one end and share a commonhinge/fold-line with the second right frame 927 and the third rightframe 930 on the other end as illustrated at FIGS. 23A through 23C.

FIGS. 24A and 24B also illustrate joints between certain frames that arenot simple hinges. In particular, the right triangular frame 924 isconnected to the first right frame 925 by a spherical joint within arod-eye 940 _(R) sliding on a shaft 942 _(R) having a first end 944 _(R)and a second end 946 _(R). Likewise, the left triangular frame 922 isconnected to the first left frame 921 (not shown at FIGS. 24A and 24B)by a spherical joint within a rod-eye 940 _(L) sliding on a shaft 942_(L) having a first end 944 _(L) and a second end 946 _(L). These twojoints effectively connect a point at the spherical joint's center to acenterline of the shaft 942, 942 _(L). A cylindrical bore through a ballof the rod-eye 940 _(L), 940 _(R) slides along a diameter of the shaft942 _(R), 942 _(L) as the first framework group 911 transforms betweenthe extended configuration and the retracted configuration. This slidingaction is illustrated at FIGS. 24A and 24B. The rod-eye 940 _(R), 940_(L) is between the first end 944 _(R), 944 _(L) and a second end 946_(R), 946 _(L) of the shaft 942 _(R), 942 _(L) when the first frameworkgroup 911 is in the extended configuration (FIG. 24A) but moves closerto the second end 946 _(R), 946L of the shaft 942 _(R), 942L when thefirst framework group 911 is in the retracted configuration (FIG. 24B).

The coordinating link 936 effectively adds a symmetric constraint to thefirst framework group 911. The symmetric constraint keeps movementwithin the first framework group 911 symmetric from right to left. Thesymmetric constraint counters the extra degrees of freedom introduced bythe fourth left frame 931 and the fourth right frame 933. The previousembodiments included three corresponding panels (instead of four) andthus did not require the symmetric constraint. By including thesymmetric constraint along with other features described above andillustrated in the figures, the seventh embodiment of the presentdisclosure also moves between the extended configuration and theretracted configuration defined by a single variable.

Providing four left frames 921, 926, 929, 931 and four right frames 925,927, 930, 933 in addition to other features of the seventh embodimentprovides other desirable benefits for certain embodiments of the presentdisclosure. These include the framework groups 911, 912, and 913producing no movement beyond the flexible covering while transitioningbetween the extended configuration and the refracted configuration. Thusno interference exists between the flexible covering and the frameworkgroups 911, 912, and 913 in any configuration. The lack of interferenceallows a flexible covering that flexes but resists stretching. The useof four left frames 921, 926, 929, 931 and four right frames 925, 927,930, 933 also provides a benefit of nesting frame pairs. In particular,when in the refracted configuration, the second left frame 926 nestswithin the first left frame 921, the second right frame 927 nests withinthe first right frame 925, the fourth left frame 931 nests within thethird left frame 929, and the fourth right frame 933 nests within thethird right frame 930.

Certain beneficial features in certain embodiments of the presentdisclosure include the gently sloping exterior surfaces of the apparatuswhen extended, the compact space it occupies when retracted, therelative simplicity of the design, the ability to use simple and lowcost components, the ability to control all panels within a panel groupwith one variable, and the ability to control all the panels within anapparatus or pair of apparatuses with one variable.

It is desirable for drag reducing devices in accordance with theprinciples of the present disclosure to be shaped to reduce the effectsof air flow separation. In certain example embodiments, drag reducingdevices in accordance with the principles of the present disclosure maydefine angles α, β, and γ (see FIGS. 1G and 1J) relative to the rearsurface of the vehicle that is less than 18 degrees, or in the range of10 to 18 degrees. In other embodiments, the angles α, β, and γ arebetween 8 and 15 degrees. In still other embodiments, the angles α, β,and γ are between 0 and 18 degrees.

When extended, drag reducing devices in accordance with the presentdisclosure are typically truncated (see FIG. 1A). In certain truncatedembodiments, the extended lengths of the drag reducing devices are suchthat the effects of drag caused by air flow separation at the truncatedends are minimal. In example embodiments suitable for tractor trailers,the drag reducing devices may have extended lengths greater than 4 feet,or in the range of 6 to 22 feet, or in the range of 8-14 feet. Vehicleshaving smaller heights and widths could be equipped with proportionallysmaller drag reduction devices. In certain embodiments, the ratio of theextended length of the drag reduction device to a reference dimension ofthe vehicle is at least 1 to 1. The reference dimension is typically thesmaller of the width or the height of the rear of the vehicle body. Inthe embodiment of FIG. 1F, the width w is the reference dimension sinceit is smaller than the height h. In other embodiments, this ratio is atleast 1.5 to 1, or at least 2 to 1, or at least 3 to 1.

In certain embodiments, drag reducing devices in accordance with thepresent disclosure may be automatically extended and/or retracted. Acontrol system may be used to automatically control extension andretraction. In certain embodiments, vehicle speed, crosswind speed, orother vehicle parameters may be used to automatically controlretraction/extension. For example, a controller may sense vehicle speed,and automatically cause retraction of the drag reducing device if thevehicle speed moves below a given speed value (e.g., 45 miles per hour).In another example, a controller may sense crosswind speed, andautomatically cause retraction if crosswinds exceed a given value (e.g.,25 miles per hour).

In many embodiments of the present disclosure, the trailer 1, with reardoors, is used as a representative vehicle. Other vehicles exist, suchas a truck with a van body, which have similar rear doors. Whereappropriate, the discussions involving the trailer 1 and/or the trailerdoors apply equally to other vehicles.

Retractable drag reducing devices in accordance with the presentdisclosure can have relatively long extended lengths as compared toretracted lengths. Certain embodiments have an extended length toretracted length ratio of at least 6 to 1. Other embodiments haveextended length to retracted length ratios of at least 10 to 1 or atleast 20 to 1.

While specific angles and lengths have been specified for certainembodiments of the present disclosure, it will be appreciated that thebroad aspects of the present disclosure are not limited to these values.

In the present disclosure, the words “a” or “an” are to be taken toinclude both the singular and the plural. Conversely, any references toplural items shall, where appropriate, include the singular.

From the foregoing it will be observed that numerous modifications andvariations can be effectuated without departing from the true spirit andscope of the novel concepts of the present invention. It is to beunderstood that no limitation with respect to the specific embodimentsillustrated is intended or should be inferred.

1. A drag reducing device for use in reducing drag on a vehicle, thedrag reducing device adapted for mounting on a substantially verticalrear end of the vehicle, the drag reducing device comprising: an upperpanel that is movable between a deployed position of the upper panel anda refracted position of the upper panel, the upper panel hingedlyattached to the substantially vertical rear end of the vehicle at afirst substantially horizontal hinge line; a lower panel that is movablebetween a deployed position of the lower panel and a refracted positionof the lower panel, the lower panel hingedly attached to thesubstantially vertical rear end of the vehicle at a second substantiallyhorizontal hinge line; a central member positioned between the upper andthe lower panels, the central member hingedly attached to thesubstantially vertical rear end of the vehicle at a hinge line; an uppermember rotatably connected to the central member at a first connectionand rotatably connected to the upper panel at a second connection; alower member rotatably connected to the central member at a thirdconnection and rotatably connected to the lower panel at a fourthconnection; wherein the upper and the lower panels, the central member,the upper member, and the lower member cooperate with each other to movethe upper and the lower panels together to the deployed positions of theupper and the lower panels respectively, and wherein the upper and thelower panels, the central member, the upper member, and the lower membercooperate with each other to move the upper and the lower panelstogether to the retracted positions of the upper and the lower panelsrespectively.